Measuring instrument.



S. HEATH. MEASURING INSTRUMENT.

APPLICATION FILED APR.20.I911.

Patented Nov. 6, 191? 2 SHEETS-SHEET 2.

UNTTEE STATE PATENT SPENCEB HEATH, OF VIASHINGTO'N, DISTRICT OF COLUMBIA, ASSIGNOR TO AMERICAN PBOPELLER AND Ii/IANUFACTURING CO., A CORPORATION GF I/IARYLAND.

B'IEASUBING INSTRUMENT.

Speeification of Letters Patent.

Patented Nov. 6,* 1917.

Original application filed August 27, 1910, Serial No. 579308. Divide and this application filed April 20,

To all whom it may camera:

Be it known that I, SPENCER HEATH, a citizen of the United States, residing at lVashington, in the District of Columbia, have invented a new and useful Measuring Instrument, of which the following is a specitication.

rThis invention relates to means for measuring propellers, and has for its object to provide accurate and convenient means for measuring the pitch, angles, etc., of a propeller at any part of the blade.

lVith the above and further objects in view which will appear, 1 have invented the subject-matter set forth by means of the accompanying drawings which form a part of this specilication and in which,

Figure l is an elevation of my improved pitch indicating means applied to a propeller blade, and

Fig. :2 shows a pitch reading instrument as used for laying oif a rough Propeller block.

The instrnmentconsists of a plate 9 carrying a pivoted arm or blade 10 and inscribed with a diagram 11 from which readings are taken for different positions of the blade. The arm 10 near its pivotal attachment 13 is provided with a spirit level 12 parallel with its length. A lug 11 stops the arm in its lowerinost position parallel with the lower edge or base 15 of the plate 9 and with this blade position the instrument may be used as an ordinary level.

The diagram 11 consists of a series of vertical nuinbered lines with the spaces between them representing units of .a propeller diameter, and a series of horizontal numbered lines marking off intervals representing units of pitch. The unnumbered light lines in each series are merely for the purpose of giving intermediate or fractional readings. The ratio between the units of pitch and the units of propeller diaineter is 1 to 311159- so that any line drawn from the pivot 13 to any intersection representing a certain pitch and diameter has the same pitch slope or inclination as a helix of corresponding diameter and pitch. To read the pitch, therefore, of any propeller blade it is only necessary to place the propeller with its axis vertical, mark off (with chalk or otherwise) intervals of blade length corresponding to different dianieters, lay the inper revolntions being known or assumed. To

Serial No. 622,184.

strument across the propeller blade at the marked-oilA points of division, raise the arm, until it is level as indicated by the bubble atl 16 and then take the vertical reading at the point where the edge of the blade or arm crosses the vertical line indicating the same diameter as the point on the propeller blade where the instrument is set. This gives at a glance the pitch readings at different points along the blade. These readings may be tabulated for reference or plotted on a diagram.

The diagram 11 on the instrument is also furnished with a scale of angles in degrees, so that the instrument may be used as a protractor as well as an indicator of pitch and the blade angle may be readin degrees for every pitch reading. The protractor scale is in two portions 17 andfllS, the portion 18 being placed more remote from the center to admit of coarser and more accurate graduations.

n Fig. 1 if the instrument rests on the blade at a point where it-sweeps a circle having a diameter of six, then the pitch is seen to be six and one-half and the blade angle nineteen degrees. If the diameter at the point measured is five, then the pitch reading is about five and one-half, the angle, of course, remaining` the same. Any units may be employed, as fee't, inches, centimeters, etc.

The instruinent may be used as a ready means for calculating the gliding` angles of any propeller blade at different points, the working pitch or actual advance forward do this the blade anglesfrom point to point on the blade are taken and noted down.b The angles of the working-pitch or of the helices traversed by the blade at corresponding i points are then taken and the difference bei tween the two sets of. readings in degrees gives .the respective gliding angles of the blade. These may be plotted for reference or comparison. To read the angle of any working pitch the arrn of the instrument is placed on that pitch reading for the given diameter and the reading of the angle in degrees for this position is taken.

The arm 10 has an additional spirit level 19 at right angles to its length and to the level 12. This level 19 is used in case the axis of the propeller to be measured should be more conveniently placed in a horizontal instead of a vertical position, as usually occurs When the propeller is mounted on a machine.

In F ig. 2 the pitch reading instrument is applied to a rough propeller block for the purpose of laying off the block so that it can be heWn down to the desired pitch at any point on the blade.

A beam 20 is provided With two rigl'it-angle members 21 and 22, one or both of' these members being slidable on the beam. Member'2l has a notch to rest'on the u-pper side of the propeller block and member 22 is-providedl With an' aWl. or marker 2l tola-y off the point down to which the block must b'e'hewn to get the desiredV pitch. T he notch 23l and marker 2l are equidistant from' the upper ends ofv members 21 and 22 and also from the` beamv 20.v

For laying off the block at any diameter or distance from the center the arm 10 is moved to the position Which indicates the pitch desired at the given diameter. l/Vith this setting the instrument is placed across the upper ends/ of members 21 and 22 as in Fig; 2, or on the beam 20 and the marker 24 is brought to the elevation at Which the bubble inA the level 12 is neutral. The point thenl indicated by the marker is the point to which the block must be heWn down to obtain thedesired pitch. This process may be repeat'ed at several places along the block corresponding to different diameters and the series of pitch points thus obta-inedl by the'marker maybe joined by a Smooth line down tolwhich the block must be heWn.

I-tis, of course; obvious,` that the parts may be sok modified that the base` of the instrument Will lie directly on the beam, or the members 21' and 22V could be integral Withk or attached directly to the lower edge V of'the plate instead of' the beam- 20.

This application is in part a division of my co-pending application filed August 27, 1910,. Serial No. 579,308.

What I claim is:

l. A screW pitch measuring instrument comprising in; combination a plate having anv extensive diagram display area and a Working edge adapted. to co-act With the' surfaces of' the scr'ew to be measured, a

blade piyoted on said plate for angular movement over said diagram display area and a leveling device mounted on said blade, said diagram' display area being provided With rec-tangular cordinate lines having a common Origin on the plate at the pivotal point of said blade, and one of the series of cordinate lines being parallel and the other perpendicular to the saidy plate, the unit space intervals between the lines in one series being related to the corresponding intervals in. the other seriesV 31. Meansfor laying off apropeller block comprising a bar; two perpendicular members mountedv thereon, one of said members having anotch andi the other having a marker,y said not'ch and m'arker. being'equidistant from the tops of a pitch reading in's'tiau'nent adaptcdito* lay across. the tops of thefm'embers, saidpitch reading instrument comprising a plate having a diagram, and4 a le'vel.'-ar.m.v adapted' to Swing' a'cross said diagri'aln;

Ar; Thef'combination with a pitch measuring instrument having av Working edge of two membersp'rojecting therefroim. said membersl being' adj ustablev along. the Working edge of` the instrument,v said instrument comprising a plate havingl a diagramV With intersecting lines'indicating! diameter and pitclr and` a pivoted devel. arin.:` adapted to' swing across'fl saidf diagram;

SPENCERv HEATH. Witnesses:

N. GUR'rIs LA-MMOND, N.. E; Cos'rnLL'o, L, C. HoLMns.

Opisf of this patent may beobtaine. fory five/cents eaeh',*by\adressingi'the:Commissioner of Patents, Washington, 11.0.

Working edge of' the n'iembers,V andv piteh reading i 

